The broad goals of this program are to coordinate and focus the experience and talents of scientists currently working in venereal disease research at several levels of biological organization, ranging from epidemiologic studies of populations to clinical investigations of individual patients, to experimental animals models, interaction of pathogens and cells in vitro, and finally to immunologic and genetic research. The specific goals are disease and problem oriented rather than phenomenologic. The individual components of the program are listed below: A. Clinical Epidemiology and Pathogenesis of Gonorrhea. B. The Genetics of Virulence Determinants in Neisseria gonorrhoeae. C. Antigenic Analysis of Neisseria gonorrhoeae. D. Simian Genital Infection Model: Neisseria and Chlamydia. E. Etiology, Clinical Manifestations, and Treatment of NGU. F. CMV, HVH, Chlamydia: Cohort Study of Infection and Disease. G. Borreliae as a Source of Vaccine for Experimental Syphilis. H. Studies on Immunity in Experimental Syphilis.